HIV-infected adults have a 1.5-to-2-fold increase in risk of myocardial infarctions (MIs) compared with uninfected adults. Our objective was to estimate the population attributable fractions (PAFs) of HIV-related and traditional MI risk factors, interpreted as the proportion of MIs that could potentially be avoided if HIV-infected adults were unexposed to these risk factors.
We included adults from 7 contributing cohorts to the NA-ACCORD with validated first occurrence of a type 1 myocardial infarction, which are MIs from plaque rupture that would be most susceptible to traditional MI risk factors. Modifiable HIV-related risk factors included CD4 <200 cells/mm3, detectable plasma HIV RNA (≥400 copies/mL), and history of clinical AIDS. Modifiable traditional risk factors included tobacco smoking, treated hypertension (HTN), hypercholesterolemia (HC, defined as use of statins or a total cholesterol >240 mg/dL), type II diabetes, stage 4 chronic kidney disease (CKD), and hepatitis C virus (HCV) infection. Cox proportional hazard models with piecewise constant baseline hazard functions were used to estimate hazard ratios (adjusted for age, sex, race, and injection drug use). These hazard ratios were combined with the prevalence of the risk factor among persons with MIs to estimate adjusted PAFs for modifiable risk factors. Smoking and HCV infection were measured at study entry. All other variables were time-updated.
A total of 29,515 adults contributed 131,137 person-years and 347 MIs; median follow up was 3.5 years. At baseline, participants who subsequently had an MI were older, more likely to be black, have smoked, had HTN, HC, diabetes, stage 4 CKD, a low CD4, a clinical AIDS diagnosis, and HCV infection. Adjusting for demographics, eliminating smoking, HTN, and HC would avert 38%, 41% and 43% of MIs, respectively (Figure 1); eliminating all three would avert 86% of MIs. HIV-related risk factors and HCV infection had smaller PAFs. A subgroup analyses accounting for BMI showed similar results, with the exception of a reduction in the PAF for HC.
Preventing smoking, hypertension, and HC each could result in a ~40% reduction in MIs among aging HIV-infected adults; further reductions in MIs can be achieved with aggressive antiretroviral management. These results underscore the need to implement traditional MI risk reduction interventions soon after prompt HIV treatment initiation in order to reduce excess MI burden among aging HIV-infected adults.